Income Taxes - Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 34.7		$ 44.7		$ 97.1		$ 87.4
Belgium [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	0.1		0.0	[1]	(0.1)		0.0	[1]
Switzerland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	0.0	[1]	(0.2)		0.0	[1]	(0.2)
Maximum [Member] | Belgium [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)			0.1				0.1
Maximum [Member] | Switzerland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.1		$ 0.1		$ 0.1		$ 0.1

[1] Pre-tax income for the respective year was less than $0.1 million.